Endocrinology of Pregnancy Flashcards
Where is tubular fluid reabsorbed and what controls this process?
Rete testis
Early epididymis
This is under the control of oestrogen
Where do you find oestrogen within the male reproductive tract?
Tubular fluid produced by sertoli cells
What stimulates the release of nutrients and other molecules (e.g. glycoproteins) into the epididymal fluid?
Androgens
What are the roles of these secreted nutrients and molecules?
Provide energy for the impending journey
Coat the surface of the spermatozoon (to protect them from the hostile environment)
Within which part of the male reproductive tract is fluid reabsorbed and secretory products put in?
Epididymis
Why is the concentration of sperm in the vas deferens higher than further down the reproductive tract?
Further down the reproductive tract, other fluids and secretory products are added thus diluting the sperm.
Why is there fibrinogen and fibrinolytic enzymes in the seminal fluid?
After ejaculation, the semen initially clots and then must be broken down
Describe the capabilities of the spermatozoa in the vas deferens.
Capable of limited movement
Limited capability to fertilise an ovum
Which steroid precursor tends to be provided by the mother for the foetus?
Pregnenolone
Which androgen is formed by the maternal and foetal adrenals?This is used as a precursor for oestrogen production.
Dehydroepiandrosterone Sulphate (DHEAS)
Which oestrogens are produced by the placenta using DHEAS from the mother and foetus?
Oestradiol
Oestrone
What is the main oestrogen of pregnancy? Describe how it is produced.
OESTRIOL
DHEAS from the foetal adrenals is conjugated in the foetal liver to form 16-alpha-hydroxy DHEAS
16-alpha-hydroxy DHEAS is then de-conjugated in the placenta and used to produce oestriol
What can be measured to gage the health of the foetus?
Oestriol: oestradiol + oestrone levels
Oestriol: total oestrogens
What biochemical change is required for contraction of the uterus during parturition?
Increase in intracellular calcium concentration
Describe how oestrogen increases the chance of contraction.
Oestrogen binds to oestrogen receptors and triggers the synthesis of prostaglandins within the endometrial cells.
Prostaglandins stimulate the release of calcium from intracellular stores.
So oestrogen tends to increase the chance of contraction
Describe how oxytocin increases the chance of contraction.
Oxytocin binds to its receptor on the endometrial cell and opens calcium channels, allowing calcium ions to move in from outside
Describe the effect of progesterone on this contraction process.
Progesterone keeps the effects of oestrogen under control
Progesterone inhibits oestrogen receptors
Progesterone inhibits the production of prostaglandins
What change occurs when the foetus reaches a particular size, which is crucial for contraction to take place?
There is a switch in steroid synthesis from progesterone synthesis to oestrogen synthesis
This leads to oestrogen dominance –> prostaglandin production –> calcium release from intracellular stores –> promotion of muscle contraction
